Regretfully, I don't have time to leave too long a review (I'm in a bit of a hurry).
That word - hurry - doesn't fit this piece though, as it definitely isn't afraid to take it's time. I like how the listener is slowly sucked into the atmosphere of the track, not knowing what to expect.
This composition sounds really experimental, but I guess that's quite often the case when it comes to the horror genre.
I'm sad to say I'm not familiar with Penderecki's work, but I'll make sure that the case doesn't remain so for too long.
This would be great background music for a horror game or movie, as I'm sure you know. It'd be cool if it looped, but that mightn't be the right thing to do for this piece. Some places stand out a bit too much for it to work. I like that though, because that makes it feel like the piece is going somewhere.
I really love the transitions between the different parts too; they work surprisingly well. Everything flows pretty smoothly. The intruments work well together, which I find really interesting.
In fact, I think that tracks like this are always interesting, because I couldn't tell you what chords I've listened to, nor how the melody goes, but what I've listened to is still music.
Last but not least, I like your use of the piano. Despite what I just said, I like that I'm actually able to grasp a few notes in this point of the piece, and a piano used in the right way is almost always a great addition to a horror track.
Great job, I've got nothing to really criticise ;)